1. Field of the Invention
The present invention relates to a defrosting apparatus of an air conditioner and a method thereof, and more particularly to a defrosting apparatus of an air conditioner and a method thereof, the apparatus and method being capable of reducing a period of time needed for carrying out a defrosting operation where the defrosting operation is carried out at a heating operation, and simultaneously increasing efficiency of the defrosting operation.
2. Description of the Related Art
Conventionally, an air conditioner includes a compressor for changing a coolant of a low-temperature and low-pressure gas state to a coolant of a high-temperature and high-pressure gas state; a condenser for changing the coolant of the high-temperature and high-pressure gas state to a coolant of a medium-temperature and high-pressure liquid state; an expansion device for changing the coolant of the medium-temperature and high-pressure liquid state to a coolant of a low-temperature and low-pressure liquid state; and a vaporizer for vaporizing the coolant of the low-temperature and low-pressure liquid state.
In a heat pump type air conditioner, operations of indoor and outdoor heat exchangers vary with a cooling or heating mode. In the heating mode, the indoor heat exchanger acts as the condenser, and the outdoor heat exchanger acts as the vaporizer. Otherwise, in the cooling mode, the indoor heat exchanger acts as the vaporizer, and the outdoor heat exchanger acts as the condenser.
A recent air conditioner can vary capacity for coolant compression of a compressor on the basis of a cooling or heating load using a plurality of compressors having different capacities, thereby improving efficiencies of cooling and heating operations.
As shown in FIG. 1, the conventional heat pump type air conditioner having a plurality of compressors includes first and second compressors 11 and 12 for compressing coolants to high-temperature and high-pressure gas coolants; an indoor heat exchanger 14 for performing heat exchange with the coolants, compressed in the first and second compressors 11 and 12, and indoor air, and condensing the coolants to a medium-temperature and high-pressure liquid coolant; and indoor fan 14a for ventilating the indoor air to the indoor heat exchanger 14, an LEV (Linear Expansion Valve) 15 for decompressing the coolant passing through the indoor heat exchanger 14 to a low-temperature and low-pressure liquid coolant; an outdoor heat exchanger 16 for performing heat exchange with the coolant passing through the LEV 15 and outdoor air; an outdoor fan 16a for ventilating the outdoor air to the outdoor hear exchanger 16; an accumulator 17 for supplying only a gas phase coolant to the first and second compressors 11 and 12 by separating a liquid coolant from a two-phase coolant passing through the outdoor heat exchanger 16; check valves 11a and 12a for preventing backflow of the coolants compressed by the first and second compressors 11 and 12; and a four-way valve 13 for changing roles of the indoor and outdoor heat exchangers 14 and 16 by switching paths of the coolants passing through the first and second compressors 11 and 12.
The heat pump type air conditioner described above carries out a defrosting operation to remove frost because the frost can be formed in the outdoor heat exchanger due to a low outdoor temperature at a heating operation.
In the defrosting operation, if a microcomputer (not shown) receives a signal generated due to frost formation in the heat exchanger, the microcomputer issues a control signal to a system controller 18. The system controller 18 enables the four-way valve 13 to switch the paths, thereby temporarily switching the heating mode of the air conditioner to the cooling mode so that high-temperature and high-pressure coolant gases compressed by the compressors 11 and 12 can be transferred to the outdoor heat exchanger 16.
Since a high-temperature coolant passes through the outdoor heat exchanger 16, the frost formation of the heat exchanger is removed.
However, where the air conditioner is switched from the heating mode to the cooling mode to perform the defrosting operation, there are problems in that a period of time required for the defrosting operation cannot be reduced and hence efficiency of the defrosting operation is degraded because an amount of coolant passing through the outdoor heat exchanger 16 is constant.
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a defrosting apparatus of an air conditioner and a method thereof, the apparatus and method being capable of reducing a period of time needed for carrying out a defrosting operation where the defrosting operation is carried out at a heating operation, and simultaneously increasing efficiency of the defrosting operation, by increasing an amount of coolant passing through an outdoor heat exchanger.
In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of a defrosting apparatus of an air conditioner having compressors, an indoor heat exchanger, an outdoor heat exchanger, a switching valve arranged between the compressors and the indoor and outdoor heat exchangers for switching a coolant path, an LEV (Linear Expansion Valve) arranged between the indoor and outdoor heat exchangers, and a system controller for controlling the switching valve where frost is formed in the outdoor heat exchangers at a heating operation and performing a defrosting operation, comprising: a temperature sensor for sensing a pipe temperature of the outdoor heat exchanger and an outdoor temperature; a comparator for comparing the sensed pipe temperature of the outdoor heat exchanger and the sensed outdoor temperature, and generating and outputting a comparison signal; and a valve controller for increasing an opening value of the LEV at a defrosting operation and decreasing the opening value of the LEV at a defrosting operation termination.
In accordance with another aspect of the present invention, there is provided a defrosting method of an air conditioner, which performs a defrosting operation by controlling a switching valve arranged between compressors and indoor and outdoor heat exchangers and switching a coolant path where frost is formed in the outdoor heat exchanger at a heating operation, comprising the steps of: a) opening an LEV (Linear Expansion Valve) arranged between the indoor and outdoor heat exchangers on the basis of a first opening value and performing the heating operation; b) sensing a pipe temperature of the outdoor heat exchanger and an outdoor temperature; and c) opening the LEV by a second opening value greater than the first opening value where the pipe temperature of the outdoor heat exchanger is a specific value or more lower than the outdoor temperature, and performing the defrosting operation.